Protective device

ABSTRACT

Protective device having a general U-shape and being associated with a longitudinal direction arranged to run along the teeth of a user along the general U-shape, the protective device including an outer, stiff material body, arranged to define a rigid outer shape of the mouthguard; and an inner material body, arranged to define an inner shape of the mouthguard, the inner material body being made from a plastic material arranged to soften when heated so as to be molded, in heated condition, onto the teeth of the user, the inner material body being arranged to cover at least part of a bottom, a front wall and a back wall of the outer material body, a part of the inner material body covering at least part of the bottom being arranged, in the cross-section, to define a shape with a front part, a back part and a relatively thicker central part.

FIELD OF THE INVENTION

The present invention relates to a protective device in the form of a mouthguard, and in particular to a mouthguard being arranged to be specifically adapted to the teeth of a user by heating the mouthguard and molding it to the user's teeth by biting (“boil and bite”).

The invention also relates to a method for manufacturing such a protective device, and furthermore to a method for using such a protective device.

BACKGROUND OF THE INVENTION

The invention is primarily directed to protective devices for use to protect the teeth and jaws of users performing various types of sports, such as contact sports, as opposed to, for instance, purely medical applications such as nightguards, dental guards for treatment of bruxism, and similar.

Conventional mouthguards include products of “boil and bite” type and custom fit type.

Custom fit type mouthguards are specifically manufactured to fit a particular user. This results in a good fit, but also in such mouthguards being expensive for the user and due to custom manufacturing the delivery time is usually long.

Boil and bite mouthguards, on the other hand, are sold in a non-customized state. Instead, they comprise a material that softens when heated (for instance, by boiling in water). The user heats the mouthguard, inserts is into her mouth and bites down. This results in the softened material assuming the shape of the user's teeth and possibly also gums. As the mouthguard cools, said material hardens, keeping its shape. As a result, the mouthguard is then specifically adapted to that particular user and ready for use.

Boil and bite type mouthguards can be made less expensive, and also more available since they are not customized at the time of sale. The customizing process also typically takes only about 5 minutes or similar, providing convenience for the user. However, they can typically not offer the fit of custom fit type mouthguards.

Custom fit type mouthguards typically provide a superior fit, but are on the other hand associated with the drawback of sometime attaching too hard to the teeth of the user, who runs the risk of having to insert her fingers into her mouth in order to loosen the mouthguard after use.

Furthermore, whereas boil and bite type mouthguards can be manufactured using relatively thin material, custom fit type mouthguards normally require a relatively thick material, of about 6-8 mm, providing a less than optimal user experience. Apart from the negative feeling of having more material in the mouth, speech and breathing can also be negatively affected by such relatively thick mouthguard material.

US 20040146836 A discloses a dental tray having a string of material at a bottom of the dental tray. For instance, the material can be a dental treatment composition.

US 20160107067 A1 discloses a method for adhering a mouth protector to the teeth of a user, including applying an adhesive to a mouth protector channel prior to insertion into the mouth of a user.

US 20040234929 A1 discloses a therapeutic teeth device arranged with a teeth channel that is filled with a therapeutic material before application into the mouth of a user.

US 20120267811 A discloses a mouthpiece arranged with a mold that is filled with a curable polymer prior to shaping to user's teeth by biting.

The present invention solves the above described problems, providing a protective device in the form of a boil and bite type mouthguard achieving excellent fit while removing one or several of said drawbacks of conventional mouthguards.

BRIEF SUMMARY OF THE INVENTION

Hence, the invention relates to a protective device in the form of a mouthguard having a general U-shape and being associated with a longitudinal direction arranged to run along the teeth of a user along said general U-shape, the protective device comprising an outer, stiff material body, arranged to define a rigid outer shape of the mouthguard; and an inner material body, arranged to define an inner shape of the mouthguard, arranged to be in direct contact with the teeth of a user during use of the mouthguard, the inner material body being made from a plastic material arranged to soften when heated so as to be molded, in heated condition, onto the teeth of the user, and when subsequently cooled to room temperature harden so as to maintain a thus molded shape corresponding to the shape of the teeth of said user, the outer material body comprising a bottom, a front wall and a back wall, each following said general U-shape, the bottom being caudally arranged during use, the front wall being ventrally arranged during use and the back wall being dorsally arranged during use, the front wall, the bottom and the back wall together forming a cross-sectional U-shape as seen in a cross-section taken perpendicularly to said longitudinal direction, the inner material body being arranged to cover at least part of said bottom, at least part of said front wall and at least part of said back wall, a part of the inner material body covering at least part of said bottom being arranged, in said cross-section taken perpendicularly to said longitudinal direction, to define a shape with a front part near the front wall, a back part near the back wall and a central part between said front part and said back part, the central part being thicker than both said front part and said back part.

In some embodiments, said cross-sectional U-shape extends along the entire longitudinal length of the bottom.

In some embodiments, the protective device comprises two longitudinal ends, defined by the combination of the front wall, the bottom and the back wall at respective longitudinal ends of the bottom, each of said dorsal ends being open ends.

In some embodiments, the front wall comprises a series of indentations provided along an edge of said front wall facing away from the bottom.

In some embodiments, a shape of an edge of the inner material follows a shape of said front wall along said edge of said front wall facing away from the bottom.

In some embodiments, a maximum thickness, as measured perpendicularly to said bottom, of said central part is at least 20% larger than a corresponding maximum thickness of said front part and/or at least 20% larger than a corresponding maximum thickness of said back part.

In some embodiments, a maximum thickness, as measured perpendicularly to said bottom, of said central part is at least 0.8 mm more than a corresponding maximum thickness of said front part and/or at least 0.8 more than a corresponding maximum thickness of said back part.

In some embodiments, a maximum thickness, as measured perpendicularly to said bottom, of said central part is at least 3 mm.

In one example, the maximum thickness of the central part is between 4.0 and 5.0 mm, such as about 4.5 mm, while the front and back parts are both between 2.0 and 3.5 mm, such as 2.4-3.3 mm.

In another example, the maximum thickness of the central part is between 3.5 and 4.1 mm, such as about 3.8 mm, while the front and back parts are both between 1.5-2.7 mm, such as 1.8-2.4 mm.

As compared to height of the front wall 112 (in a cranial direction of the wearing user), such as to a maximum height of the front wall 112, for instance a maximum height of the front wall 112 near a dorsal (of the wearing user) end of the front wall 112, the maximum thickness of the central part may be between 18-30%.

In some embodiments, a wall thickness of said inner material body is substantially constant, such as varies only within 10% or less, across the whole mouthguard, apart from said central part where the wall thickness of the inner material body is locally thicker.

In some embodiments, a total cross-sectional area of said central part, as seen in a cross-section taken perpendicularly to said longitudinal direction, is between 10 mm² and 30 mm².

In some embodiments, said central part extends uninterrupted, such as with a substantially constant cross-section, along the entire mouthguard, along said longitudinal direction.

In some embodiments, the outer material body is less than 1.2 mm thick.

In some embodiments, the outer material body has a shore durometer of less than 80, such as between 60 and 80, such as between 65 and 75, such as about 70.

In some embodiments, the outer material body is made from at least 80% TPE (thermoplastic elastomer), such as between 85% and 95% TPE.

In some embodiments, the outer material body is made from a mixture of TPE and EBA (ethylene butyl acrylate).

In some embodiments, the inner material body is made from at least 80% EVA (ethylene vinyl acetate), such as between 85% and 95% EVA.

In some embodiments, the inner material body is made from a mixture of EVA and PCL (polycaprolactone).

Furthermore, the invention relates to a m method of producing a protective device of said type, the method comprising providing the outer material body so as to define the rigid outer shape of the mouthguard; and forming the inner material body on the outer material body, wherein a part of the inner material body covering at least part of said bottom, in said cross-section taken perpendicularly to said longitudinal direction, being formed to define a shape with a front part near the front wall, a back part near the back wall and a central part between said front part and said back part, the central part being thicker than both said front part and said back part.

Moreover, the invention relates to a method of using a protective device of said type, the method comprising heating the protective device to a temperature at which the inner material body softens; inserting the protective device into the mouth of a user, and the user biting down on the protective device so that the inner material body is molded, in heated condition, onto the teeth of the user, assuming a molded shape corresponding to the teeth of the user; and subsequently cooling the protective device to room temperature, whereby the inner material body hardens so as to maintain said molded shape.

In the following, the invention will be described in detail, with reference to exemplifying embodiments of the invention and to the enclosed drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a first perspective view of a protective device according to the present invention;

FIG. 2 is a second perspective view of the protective device illustrated in FIG. 1 ;

FIG. 3 is the same perspective view as shown in FIG. 1 , but with a cross-section removed;

FIG. 4 is the same perspective view as shown in FIG. 1 , but showing only an outer material body;

FIG. 5 is the same perspective view as shown in FIG. 1 , but showing only an inner material body;

FIG. 6 is a flowchart illustrating a first method according to the invention; and

FIG. 7 is a flowchart illustrating a second method according to the invention.

It is noted that all FIGS. 1-5 share the same reference numerals for same parts.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Hence, the present invention relates to a protective device in the form of a mouthguard 100 having a general U-shape and being associated with a longitudinal direction L arranged to run along the line of teeth of a user along said general U-shape. Such a U-shape is illustrated in the Figures, where it is particularly noted that the longitudinal direction L is curved along said U-shape. Generally U-shaped mouthguards and other dental devices are well-known per se.

Herein, the reference numeral 100 is used interchangeably to denote the protective device according to the invention and specifically for the specific mouthguard embodiment example illustrated in FIGS. 1-5 .

The protective device 100 comprises an outer, stiff material body 110, arranged to define a rigid outer shape of the mouthguard 100. As is perhaps best illustrated in FIG. 4 , the outer body 110 generally defines a U-shaped channel having a bottom 111, a front wall 112 and a back wall 113. Each of said bottom 111, front wall 112 and back wall 113 follows said general U-shape, providing a cross-sectional shape, perpendicularly to said longitudinal direction L that is approximately U-shaped at each point along said longitudinal direction L.

During use, the bottom 111 is caudally arranged during use by said user, while the front wall 112 is ventrally arranged during use by the user and the back wall 113 is dorsally arranged during use by the user.

Said front wall 112, bottom 111 and back wall 113 together form said cross-sectional U-shape as seen in the cross-section 114 taken perpendicularly to said longitudinal direction L. Two examples of such cross-sections 114, taken at different longitudinal L positions near respective ends 101, 102, are shown in FIG. 3 .

Hence, the protective device 100 is arranged to be worn on the upper teeth of the user, and stay in this position using a snug shape fit as described below.

Alternatively, it is foreseeable that the protective device 100 is arranged to be worn on the bottom teeth of the user, in which case everything that is said herein is analogously applicable.

The protective device 100 furthermore comprises an inner material body 120, arranged to define an inner shape of the mouthguard 100, and arranged to be in direct contact with the teeth of the user during use of the mouthguard 100, preferably the upper teeth of the user as mentioned above.

The inner material body 120 is made from a plastic material arranged to soften when heated so as to be molded, in heated condition, onto said teeth of the user, such as by biting, and when subsequently cooled to room temperature harden so as to maintain a thus molded shape corresponding to the shape of said teeth of the user.

As opposed to the inner material body 120, the outer material body 110 is made from a material that does not soften to the extent so that it can be permanently/non-reversibly reshaped by such molding/biting when heated.

The inner material body is arranged to cover, on the inside of said cross-sectional U-shape defined by the outer material body 110, at least part of said bottom 111, at least part of said front wall 112 and at least part of said back wall 113. Preferably, the bottom 111, front wall 112 and back wall 113 together cover at least 50%, even more preferably at least 80%, even more preferably at least 90%, of the total inside U-shaped surface of the outer material body 110. The inner material body 120 may extend at least halfway up along the front wall 112 as well as the back wall 113 from the bottom 111 of the outer material body 110. As is illustrated in FIG. 5 , the inner material body 120 may form a contiguous body, preferably without any through holes.

Specifically, a part of the inner material body 120 covering at least part of said bottom 111 is arranged, in said U-shaped cross-section 114 taken perpendicularly to said longitudinal direction L, to define a shape with a front part 121 near the front wall 112, a back part 122 near the back wall 113 and a central part 123 between said front part 112 and said back 113 part. The central part 123 is thicker, in a direction perpendicular to said bottom 111, than both said front part 121 and said back part 122.

As mentioned, the inner material body 120 becomes soft when heated, such as when heated above room temperature, such as when it is boiled in water. In a softened state, it will non-reversibly deform when pressed against the teeth, and possibly also to the gums, of the user, for instance by the user biting down on the mouthguard 100 being placed between the teeth of the user, so as to assume a shape that is complementary to said teeth and possibly also to said gums. Once cooled again, the assumed complementary shape will remain as the inner material body 120 again hardens as a result of said cooling. Therefore, as the user then inserts the mouthguard 100 into her mouth, the fit to the teeth, and possibly also to the gums of the user, will be precise. This process of heating, shaping and re-cooling of a mouthguard is sometimes called “boil and bite”.

The present inventor has discovered that, thanks to the inner material body 120 being thicker at said central part 123, the softened inner material will more readily adapt its shape to said teeth, the inner material being pressed up between the teeth and also up on both the front and back side of each tooth, so as to very efficiently fill any voids while minimizing the risk of inner material overflow at the top of said U-shape of the outer material body 110.

The result is a very snug fit using a minimum of material, in particular a minimum of inner material. Since less material is used in the mouthguard 100, the fit of the mouthguard 100 is more agreeable to the user.

As compared to a custom-molded mouthguard, being produced already from the outset with a permanent inside shape adapted to the teeth of the user rather than by said “boil and bite” process, the present protective device 100 can also be designed to have thinner overall material thickness, further reducing the amount of material in the mouth of the user, which is advantageous.

As is illustrated in the Figures, the central part 123 may be provided on top of said bottom 111, as a locally bulging part of the inner material body 120.

As is also illustrated in the Figures, the relatively thicker (or deeper) central part 123 of the inner material body 120 in combination with the relatively thinner (or shallower) front 121 and back 122 parts, form an elongated ridge, running in the longitudinal direction L along the mouthguard 100, such as along the entire or substantially entire (such as at least 90%) of the longitudinal L length of the mouthguard 100, the ridge having a longitudinally L extending trench on either side thereof.

As viewed in said cross-section 114 taken perpendicularly to the longitudinal direction L, the ridge (central part 123) may have a non-rectangular (or even non-linear) shape, for instance a bulging shape, such as a semi-circular or substantially semi-circular shape. This provides for optimum filling out of voids during shaping.

As the mouthguard 100 is pressed onto said teeth, each tooth will be pressed down onto the central part 123 and as a result push the inner body 120 material out in all lateral (in a plane parallel to the bottom 111) directions. As the teeth are further pressed into the mouthguard 100, said trenches become filled and the softened inner material will continue to be pressed up between the teeth, in front of the teeth and at the back of the teeth, providing a very efficient filling of any voids.

The total volume of the inner material body 120 is selected so that it, together with the total expected volume of the teeth (including part of the gums, as the case may be) when fully pressed down into the mouthguard 100, completely, or substantially completely, fills the cross-sectional U-shape defined by the outer material body 110.

As discussed above, the cross-sectional U-shape 114 may extend along the entire longitudinal L length of the bottom 111, and may have an overall shape that is the same or substantially the same along this entire length.

Moreover, the protective device 100 may comprise two longitudinal ends 101, 102, defined by the combination of the front wall 112, the bottom 111 and the back wall 113 at respective longitudinal L ends of the bottom 111, each of said dorsal ends 101, 102 being open ends in the sense that the mouthguard 100 lacks terminating (vertical) end walls.

As is also illustrated in the Figures, the front wall 112 may comprise a series of indentations 115 provided along an edge of said front wall 112 facing away from the bottom 111, this edge being a top edge when worn by the user. In the Figures, three such indentations 115 are illustrated, but it is realized that between 2 and 6 indentations may be useful for different types of protective devices. The purpose of the indentations 115 is to provide space for any smaller amounts of surplus inner body 120 material when the user bites down on the mouthguard 100, in turn providing a means to cater for different teeth constitutions by one single mouthguard 100 design.

It is furthermore preferred that a shape of a corresponding edge of the inner material body 120 follows a shape of said front wall 112 along said edge of said front wall 112 facing away from the bottom 111, so that an upper front edge (during use) of the mouthguard 100 as a whole is shaped accordingly, with indentations corresponding to indentations 115 in the outer material body 110. This is illustrated in the Figures.

One or more corresponding indentations may also be arranged in the back wall 113.

A maximum thickness, as measured perpendicularly to said bottom 111, of the central part 123 may be at least 20% larger than a corresponding maximum thickness (also perpendicularly to the bottom 111) of said front part 121 and/or at least 20% larger than a corresponding maximum thickness (perpendicularly to the bottom 111) of said back part 122.

Correspondingly, a maximum thickness, as measured perpendicularly to said bottom 111, of the central part 123 may be at least 0.8 mm thicker than a corresponding maximum thickness (perpendicularly to the bottom 111) of said front part 121 and/or at least 0.8 thicker than a corresponding maximum thickness (perpendicularly to the bottom 111) of said back part 122. In some embodiments, one or both of said thickness differences can be between 0.8 and 2.0 mm, such as between 1.0 and 1.6 mm, such as about 1.4 mm.

Furthermore, a maximum thickness, as measured perpendicularly to said bottom 111, of said central part 123 may be at least 3 mm. As an example, for smaller mouthguards 100 (such as for children) said maximum thickness may be between 3 and 3.6 mm. For larger mouthguards, on the other hand, said maximum thickness may be between 4.0 and 4.6 mm. The present inventor does not envision having to use more than about 5.0 mm of total inner material body 120 thickness even for larger mouthguards 100.

In general, the inner material body 120 may form a body of material having substantially the same material thickness (as measured perpendicularly from the bottom 111, the front wall 112 or the back wall 113 depending on what part of the inner material body 120 being measured), apart from the thicker ridge described above. Specifically, a wall thickness of the inner material body 120 may be constant or substantially constant, such as it varies only within 10% or less, across the whole inner material body (across the whole mouthguard 100), apart from at said central part 123 where the wall thickness of the inner material body 120 is locally thicker, such as to form said ridge as discussed above.

In some embodiments, a total cross-sectional area of said central part 123, as seen in said U-shaped cross-section 114 taken perpendicularly to said longitudinal direction L, is between 10 mm² and 30 mm². It is realized that the central part 123 is preferably connected to both the front part 121 and the back part 122, why it may be difficult to exactly define where the central part 123 ends and the front part 121 and back part 122 begin. Preferably, the central part 123 occupies about 25-50% of the total lateral (horizontal) extension of the bottom 111 in said U-shaped cross-section 114. A width of the central part 123 at any point along the longitudinal direction L may be defined as a width of an inner material body 120 part that is vertically thicker (ridge) as compared to corresponding side parts (trenches).

The central part 123, and hence said ridge, may advantageously extend uninterrupted, preferably with a constant or substantially constant cross-section 114, along the entire mouthguard, along said longitudinal direction L. The corresponding then applies to said trenches.

In some embodiments, the outer material body 110 is everywhere less than 1.2 mm thick, such as about 0.9-1.0 mm thick (see FIG. 4 ). The total thickness of the protective device 100 at the front wall 112 and/or at the back wall 113, counting both the outer material body 110 and the inner material body 120, may in some embodiments be at the most 2.2 mm thick, such as at the most 2.0 mm thick. This thickness may in some embodiments be at least 1.8 mm.

In addition to said shape of the inner material body 120, with said thicker central part 123, the present inventor has also discovered that certain types and combinations of materials provide a superior fit and user experience in a protective device 100 of the present type.

Regarding first the outer material body 110, it may be manufactured from a material having a shore durometer (hardness) of less than 80, preferably between 60 and 80, preferably between 65 and 75, such as about 70.

For instance, the outer material body 110 may be made from at least 80% TPE (thermoplastic elastomer, for instance Dryflex® 500700S available from Hexpo TPE AB, Åmål, Sweden), preferably between 85% and 95% TPE. Specifically, a mixture of a majority of TPE and a minority of EBA (ethylene butyl acrylate, such as Lucofin® 1400HN, available from Lucobit AG, Wesseling, Germany) has been found advantageous, in particular a mixture of 90% TPE and 10% EBA. The EBA constituent provides for a harder surface, while the TPE provides flexibility, the combination being advantageous.

The outer material body 110 may be formed using injection molding.

The specific combination of a relatively thin outer material body 110 with a relatively soft outer material provides for a flexible and agreeable protective device 100 of the present type.

The inner material body 120 may, in some embodiments, be made from at least 80% EVA (ethylene vinyl acetate, such as EVA1159, available from Hanwha Chemical, Hanwha, Korea), preferably between 85% and 95% EVA. In some embodiments, a mixture of a majority of EVA and a minority of PCL (polycaprolactone, such as Capa 6500D, available from Perstorp AB, Perstorp, Sweden), such as 90% EVA and 10% PCL, has been found to be advantageous.

It is understood that both the outer material body 110 and the inner material body 120 may comprise smaller amounts of various additives, depending on the specific application of the present invention, including coloring agents.

As is illustrated in FIGS. 1-5 , the central part 123 may vary along the longitudinal direction. In some embodiments, the central part 123, in said cross-section 114, has a constant or substantially constant height, as a function of longitudinal direction L. Alternatively, the central part 123 has a larger height further away from front teeth of a user wearing the protective device 100, at a part of the protective device 100 being in contact with molars of the user in question, in other words closer to the “ends of the general U-shape”.

In some embodiments, the central part 123 forms a thickening or ridge, in said cross-section 114, which varies along the longitudinal direction L. In general, it is preferred that parts of the central part 123 being in contact with molars of the wearing user have a larger width, in said cross-section 114, as compared to parts of the central part 123 being in contact with front teeth of the user in question. As is shown, for instance, in FIG. 5 , the central part 123 defines, along said longitudinal direction L, a tapered form which is wider towards the “ends of the general U-shape” as compared to at a “central part of the general U-shape”.

Such wider and/or higher central part 123 near the molars of a wearing user can be combined with the front wall 112 and the back wall 113 of the outer material body 110 defining, in said cross-section 114, a U-shape which is narrower near or at the front teeth of a wearing user as compared to a relatively wider defined U-shape, in said cross-section 114, near or at the molars of the wearing user.

This provides a better fit.

The central part 123 may run interruptedly at least along the entire part of the protective device 100 arranged to be in contact with the wearing user's molar teeth on either side of the user's yaw, along the longitudinal direction L.

FIG. 6 illustrates a method according to the present invention, for producing a protective device 100 of the type described herein.

In a first step, the method starts.

In a subsequent step, the outer material body 110 is provided so as to define the rigid outer shape of the mouthguard. The outer material body 110 may be formed using injection molding.

In a subsequent step, the inner material body 120 is formed on the outer material body, such as also by injection molding.

As described above, a part of the inner material body 120 covering at least part of said bottom 111, in said cross-section 114 taken perpendicularly to said longitudinal direction L, being formed to define a shape with the front part 121 near the front wall 112, the back part 122 near the back wall 113 and the central part 123 between said front part 121 and said back part 122, the central part 123 being thicker than both said front part 121 and said back part 122.

In a subsequent step, the method ends.

FIG. 7 illustrates another method according to the present invention, f using a protective device 100 of the type described herein and which may have been produced using a method of the type illustrated in FIG. 6 .

In a first step, the method starts.

In a subsequent step, the protective device 100 is heated to a temperature at which the inner material body 120 softens, such as by boiling in water. Depending on the materials used, the protective device 100 is preferably heated to a temperature of at least 50° C., but not to more than 105° C. Such heating will make the inner material body 120 significantly softer than the outer material body 110.

In a subsequent step, the protective device 100 is inserted into the mouth of a user, and the user bites down on the protective device 100 so that the inner material body 120 as a result is molded, in said heated condition, onto the teeth of the user, assuming a molded shape corresponding to the teeth of the user, and possibly also of the gums of the user.

In a subsequent step, the protective device 100 is again cooled to room temperature, whereby the inner material body 120 hardens so as to maintain said molded shape.

In a subsequent step, the method ends.

It is understood that the present protective device 100 is generally provided in an unmolded state, illustrated in FIGS. 1-5 , that needs to be specifically adapted to the user. After heating and molding (“boild and bite”), the protective device 100 will be permanently tailored to the particular user performing this molding.

Above, preferred embodiments have been described. However, it is apparent to the skilled person that many modifications can be made to the disclosed embodiments without departing from the basic idea of the invention.

For instance, the protective device 100 may comprise additional parts in addition to the ones described above. The shape of the protective device 100 may vary as compared to the example shown in the Figures.

In general, all that has been said in relation to the protective device 100 is equally applicable to the methods for production and use, and vice versa.

Hence, the invention is not limited to the described embodiments, but can be varied within the scope of the enclosed claims. 

1. Protective device in the form of a mouthguard having a general U-shape and being associated with a longitudinal direction arranged to run along the teeth of a user along said general U-shape, the protective device comprising an outer, stiff material body, arranged to define a rigid outer shape of the mouthguard; and an inner material body, arranged to define an inner shape of the mouthguard, arranged to be in direct contact with the teeth of a user during use of the mouthguard, the inner material body being made from a plastic material arranged to soften when heated so as to be molded, in heated condition, onto the teeth of the user, and when subsequently cooled to room temperature harden so as to maintain a thus molded shape corresponding to the shape of the teeth of said user, the outer material body comprising a bottom, a front wall and a back wall, each following said general U-shape, the bottom being caudally arranged during use, the front wall being ventrally arranged during use and the back wall being dorsally arranged during use, the front wall, the bottom and the back wall together forming a cross-sectional U-shape as seen in a cross-section taken perpendicularly to said longitudinal direction, the inner material body being arranged to cover at least part of said bottom, at least part of said front wall and at least part of said back wall, a part of the inner material body covering at least part of said bottom being arranged, in said cross-section taken perpendicularly to said longitudinal direction, to define a shape with a front part near the front wall, a back part near the back wall and a central part between said front part and said back part, the central part being thicker than both said front part and said back part.
 2. The protective device according to claim 1, wherein said cross-sectional U-shape extends along the entire longitudinal length of the bottom.
 3. The protective device according to claim 2, wherein the protective device comprises two longitudinal ends, defined by the combination of the front wall, the bottom and the back wall at respective longitudinal ends of the bottom, each of said dorsal ends being open ends.
 4. The protective device according to claim 1, wherein the front wall comprises a series of indentations provided along an edge of said front wall facing away from the bottom.
 5. The protective device according to claim 4, wherein a shape of an edge of the inner material follows a shape of said front wall along said edge of said front wall facing away from the bottom.
 6. The protective device according to claim 1, wherein a maximum thickness, as measured perpendicularly to said bottom, of said central part is at least 20% larger than a corresponding maximum thickness of said front part and/or at least 20% larger than a corresponding maximum thickness of said back part.
 7. The protective device according to claim 1, wherein a maximum thickness, as measured perpendicularly to said bottom, of said central part is at least 0.8 mm more than a corresponding maximum thickness of said front part and/or at least 0.8 more than a corresponding maximum thickness of said back part.
 8. The protective device according to claim 1, wherein a maximum thickness, as measured perpendicularly to said bottom, of said central part is at least 3 mm.
 9. The protective device according to claim 1, wherein a wall thickness of said inner material body is substantially constant, such as varies only within 10% or less, across the whole mouthguard, apart from said central part where the wall thickness of the inner material body is locally thicker.
 10. The protective device according to claim 1, wherein a total cross-sectional area of said central part, as seen in a cross-section taken perpendicularly to said longitudinal direction, is between 10 mm² and 30 mm².
 11. The protective device according to claim 1, wherein said central part extends uninterrupted, with a substantially constant cross-section, along the entire mouthguard, along said longitudinal direction.
 12. The protective device according to claim 1, wherein the outer material body is less than 1.2 mm thick.
 13. The protective device according to claim 1, wherein the outer material body has a shore durometer of less than
 80. 14. The protective device according to claim 13, wherein the outer material body is made from at least 80% TPE (thermoplastic elastomer).
 15. The protective device according to claim 14, wherein the outer material body is made from a mixture of TPE and EBA (ethylene butyl acrylate).
 16. The protective device according to claim 1, wherein the inner material body is made from at least 80% EVA (ethylene vinyl acetate).
 17. The protective device according to claim 1, wherein the inner material body is made from a mixture of EVA and PCL (polycaprolactone).
 18. A method of producing a protective device according to claim 1, the method comprising providing the outer material body so as to define the rigid outer shape of the mouthguard; and forming the inner material body on the outer material body, wherein a part of the inner material body covering at least part of said bottom, in said cross-section taken perpendicularly to said longitudinal direction, being formed to define a shape with a front part near the front wall, a back part near the back wall and a central part between said front part and said back part, the central part being thicker than both said front part and said back part.
 19. A method of using a protective device according to claim 1, the method comprising heating the protective device to a temperature at which the inner material body softens; inserting the protective device into the mouth of a user, and the user biting down on the protective device so that the inner material body is molded, in heated condition, onto the teeth of the user, assuming a molded shape corresponding to the teeth of the user; and subsequently cooling the protective device to room temperature, whereby the inner material body hardens so as to maintain said molded shape. 